1. Field of the Invention
The present invention relates to a boiler. More specifically, the present invention relates to a boiler that can realize a reduction in emission of harmful substances by using a liquid fuel such as kerosene or A-type heavy oil.
2. Description of the Related Art
A boiler equipped with a boiler body having a group of water tubes arranged in an annular fashion has conventionally been well known. Generally speaking, in such a boiler, a burner is arranged at the center of the group of water tubes. That is, in a boiler of this construction, the central portion of the group of water tubes arranged in an annular fashion functions as a combustion chamber for burning the fuel supplied from the burner.
In connection with a case in which a gas fuel is used as a burner fuel, a number of proposals have been made regarding a technology for achieving an improvement in combustion property and a technology for reducing the generation of harmful substances (such as NOx, CO, and soot) (see, for example, JP 08-61614 A), and some of those proposals have proved effective.
However, despite the various proposals made up to now, regarding the boiler equipped with a combustion device using a liquid fuel such as kerosene or A-type heavy oil, the technology for achieving an improvement in combustion property and the technology for reducing the generation of harmful substances (such as NOx, CO, and soot) have made less progress than those for combustion devices using a gas fuel.
Further, in the above-mentioned boiler formed by using a boiler body having a group of water tubes arranged in an annular fashion, depending upon a position of a gas discharge port provided in the boiler body, the gas produced by the burner tends to be drawn in a specific direction (mainly in a direction in which the gas discharge port is provided), which may adversely affect the combustion performance of the burner.